<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>拖动的模态框</title>
    <style>
        .login-header {
            width: 100%;
            text-align: center;
            height: 30px;
            font-size: 24px;
            line-height: 30px;
        }

        ul,
        li,
        ol,
        dl,
        dt,
        dd,
        div,
        p,
        span,
        h1,
        h2,
        h3,
        h4,
        h5,
        h6,
        a {
            padding: 0px;
            margin: 0px;
        }

        .login {
            /* 默认隐藏 */
            display: none;
            width: 512px;
            height: 280px;
            position: fixed;
            border: #ebebeb solid 1px;
            left: 50%;
            top: 50%;
            background: #ffffff;
            box-shadow: 0px 0px 20px #ddd;
            z-index: 9999;
            transform: translate(-50%, -50%);
        }

        .login-title {
            width: 100%;
            margin: 10px 0px 0px 0px;
            text-align: center;
            line-height: 40px;
            height: 40px;
            font-size: 18px;
            position: relative;
            cursor: move;
        }

        .login-input-content {
            margin-top: 20px;
        }

        .login-button {
            width: 50%;
            margin: 30px auto 0px auto;
            line-height: 40px;
            font-size: 14px;
            border: #ebebeb 1px solid;
            text-align: center;
        }

        .login-bg {
            /* 默认隐藏 */
            display: none;
            width: 100%;
            height: 100%;
            position: fixed;
            top: 0px;
            left: 0px;
            background: rgba(0, 0, 0, .3);
        }

        a {
            text-decoration: none;
            color: #000000;
        }

        .login-button a {
            display: block;
        }

        .login-input input.list-input {
            float: left;
            line-height: 35px;
            height: 35px;
            width: 350px;
            border: #ebebeb 1px solid;
            text-indent: 5px;
        }

        .login-input {
            overflow: hidden;
            margin: 0px 0px 20px 0px;
        }

        .login-input label {
            float: left;
            width: 90px;
            padding-right: 10px;
            text-align: right;
            line-height: 35px;
            height: 35px;
            font-size: 14px;
        }

        .login-title span {
            position: absolute;
            font-size: 12px;
            right: -20px;
            top: -30px;
            background: #ffffff;
            border: #ebebeb solid 1px;
            width: 40px;
            height: 40px;
            border-radius: 20px;
        }
    </style>
</head>
<body>
    <div class="login-header"><a id="link" href="javascript:;">点击，弹出登录框</a></div>
    <div id="login" class="login">
        <div id="title" class="login-title">登录会员
            <span><a id="closeBtn" href="javascript:void(0);" class="close-login">关闭</a></span>
        </div>
        <div class="login-input-content">
            <div class="login-input">
                <label>用户名：</label>
                <input type="text" placeholder="请输入用户名" name="info[username]" id="username" class="list-input">
            </div>
            <div class="login-input">
                <label>登录密码：</label>
                <input type="password" placeholder="请输入登录密码" name="info[password]" id="password" class="list-input">
            </div>
        </div>
        <div id="loginBtn" class="login-button"><a href="javascript:void(0);" id="login-button-submit">登录会员</a></div>
    </div>
    <!-- 遮盖层 -->
    <div id="bg" class="login-bg"></div>
    <script>
         /*
            需求:
                1. 默认 id 是 login 和 bg 的两个 div 隐藏。
                2. 点击对应的 link ，显示两个 div 
                3. 点击 关闭的 id 是 closeBtn 的 a 标签，隐藏两个 div
                4. 鼠标按下登录会员(title)的元素，可以拖动模态框。
                    鼠标按下: 鼠标在页面的坐标
                    鼠标移动: 移动 div
                    鼠标弹起: 解除事件绑定
                    模态框的坐标 = 鼠标在页面的坐标 -  鼠标在盒子内的坐标
                    盒子内的坐标 =  鼠标在页面坐标 -  盒子偏移量
        */

    let login = document.querySelector('#login');
    let bg = document.querySelector('#bg');
    let link = document.querySelector('#link');
    let closeBtn = document.querySelector('#closeBtn');
    let titlt = document.querySelector('#title');
    // 点击显示
    // login.style.display = 'none';
    // bg.style.display = 'none';

    link.addEventListener('click',function(){
        login.style.display = 'block';
        bg.style.display = 'block'
    });
    // 点击关闭
    closeBtn.addEventListener('click',function(){
        login.style.display = 'none';
        bg.style.display = 'none';
    });


    title.addEventListener('mousedown',function(e){
       // 盒子内的坐标 =  鼠标在页面坐标 -  盒子偏移量
       let x = e.pageX - login.offsetLeft;
       let y = e.pageY - login.offsetTop;
    // 鼠标移动
    document.addEventListener('mousemove',move);
    function move(e1){
        // 模态框的坐标 = 鼠标在页面的坐标 - 鼠标在盒子内的坐标
        let divX = e1.pageX - x;
        let divY = e1.pageY - y;
        login.style.left = divX + 'px';
        login.style.top = divY + 'px';
    }
    // 鼠标弹起，解除事件绑定
    document.addEventListener('mouseup',function(e){
        document.removeEventListener('mousemove',move)
    });
});
    </script>
</body>
</html>